On 12/9/18 7:12 AM, EVDL Administrator via EV wrote:
On 9 Dec 2018 at 3:30, paul dove via EV wrote:
(Eight hours of charging TeslaTMs Model 3 from a wall socket will give
you your expected 200-plus miles of range.) Someone's math is off. You
can only get 1KW/h from a wall socket. Maybe 30 miles in 8 hours.
This statement isn't quite accurate.
First, there's no such unit as "KW/h." That has to be a typo. It's like
saying "horsepower per minute."
KWh doesn't work, either. The unit you're looking for is kW -- kilowatts.
Second, it all depends on what kind of "wall socket" it is. Behind my range
on the wall is a receptacle that will deliver 9.6kW (at the NEC required 80%
demand factor) for as long as you wish. Allowing for 90% charging
efficiency, that would charge a Tesla 50kWh battery to 80% SOC in 5 hours
and 48 minutes.
Third, you're a little low even for a regular 20 amp branch-circuit
receptacle. As long as it's a 20 amp rated receptacle, it can deliver up to
80% of the circuit's rated capacity -- 1.92kW -- for an indefinite period.
Even a 15 amp receptacle can give you up to 1.44kW continuously.
Using Tesla supplied 120vac equipment, which will not do more than 12
amps, a Model 3 charges at about 5mph on a "pretty good" 120vac outlet.
Teslas will reduce current draw if there is much voltage drop. So the
stated 200 miles in 8 hours seems inaccurate; 200 miles should take more
like 40 hours.
EVs with 50+ kwh batteries can not be practically be charged on 120vac
if a large fraction of battery capacity is used daily.
One advantage to a Model 3 over a Model S/X is the faster charging due
to higher efficiency. More range added per unit time. On 120vac, the S
will do 3-4 mph. The 3, around 5 mph. At a well functioning 120kw
SuperCharger, a 3 can reach about 450 mph while a S rarely reaches 400 mph.
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